The Wave by Algernon Blackwood

With Tony as guide they took their fill of wonder. The principal expeditions were made alone, introducing Tom to the marvels of ancient Egypt which they already knew. On the sturdiest donkey Thebes could furnish, he raced his cousin across the burning sands, Madame Jaretzka following in a sand-cart, her blue veil streaming in the cool north wind. They played like children, defying the tide of mystery that this haunted land pours against the modern human soul, while yet the wonder and the mystery added to their enjoyment, deepening their happiness by contrast.

They ate their "al fresco" luncheons gaily, seated by hoary tombs that opened into the desolate hills; kings, priests, princesses, dead six thousand years, listening in caverns underground to their careless talk. Yet their gaiety had a hush in it, a significance behind the sentences; for even their lightest moments touched ever upon the borders of an awfulness that was sublime, and all that they said or did gained this hint of deeper value -- that it was set against a background of the infinite, the deathless.